Experimental Study On The Headcut Scour Velocity Of The Desert Acolian Sand

The main factors on the failure patterns and headcut scour velocity with the drop terrain under the concentrated flow are studied by indoor and outdoor scouring experience.The change rule of the headcut scour velocity of the desert acolian sand under the different single width flow,different initial drop is analyzed,and the influence that water content and compactness on the headcut scour velocity is discussed,combined with the experimental data,a formula for estimating the scour velocity of desert aeolian sand is proposed.The main results are as follows:?1?Under the concentrated water erosion,the desert aeolian sand with drop terrain has a slightly slow surface erosion rate and a serious scouring of the end of the step-down floor,which is only at the 0.22%⁰.79%of the headcut scour velocity,the headcut scour has a great harm on the safety of the project.?2?The headcut scour velocity of the desert aeolian sand is not only related to the flow of single width,but also related to the initial fall of the falling ridge,and it increases with the increase of the flow rate of single width and the increase of the initial drop.The curve of the relationship between the headcut scour velocity of desert aeolian sand with the single width flux and the initial fall is a convex power function curve.?3?The water content and compactness of the desert aeolian sand have a certain affect on the headcut scour velocity,compared with the dry sand,when the aeolian sand has a certain water content and the density is large,headcut scour velocity decreases obviously.?4?The change rule of the headcut scour velocity obtained from model test results and field test is basically consistent with each other,but the aeolian sand consolidation degree of natural state is high,the density is larger,and the sand below the surface has a certain water content,therefore,compared with the model test,which is not easy to be scoured.?5?Based on the data obtained from the experiment,combined with the test verification,the formula for estimating the scouring velocity of the desert aeolian sand is obtained as follow:V_x=C₀q^0.4H.⁰².Where,C₀is the coefficient of headcut migration related to the structure and state of the desert aeolian sand,and its value varies with the water content and density of desert aeolian sand.